1. Field of the Invention
The present invention relates to a process for the production of grafted saplings of ligneous or semi-ligneous plants, and more especially of vine, and to the saplings obtained.
2. Discussion of Background and Material Information
The phylloxera appeared in France in 1866 and destroyed the vineyards completely in 1914. Their restoration could only be ensured by starting grafting French vine-plants onto American varieties or hybrids resistant to the insect. This grafting consists of joining the stock which will be buried and which will grow roots to the scion which will form the above-ground part and which will bear grapes.
Up to date, the method used is approximately the same as the one which was used for restoring French vineyards. Grafting is carried out on mature material at the end of winter by joining a shoot of American stock having a length of 20 to 30 cm to a scion of 4 to 5 cm which has one bud, of a variety of Vitis vinifera. The unit is then subjected to stratification in order to produce a join callus at the point of grafting. 15 to 21 days later the graftings are planted either in the greenhouse or in the field in order to promote root production, while the bud of the scion starts to grow in the course of these operations. This traditional grafting technique gives grafted plants ready for planting in 6 or 12 months, but with fairly low success rates, in the order of 30-35%.
The development of novel technologies, in particular IN VITRO culture, for the production of vine saplings has led to a study of novel grafting techniques.
Vegetative IN VITRO multiplication has enabled the said method of grafting of green wood to be put into practice. This technique has two major disadvantages:
grafting being being carried out on a rooted stock, it is necessary to produce all the stock required in the production by IN VITRO methods,
the 7 or 8 eyes at the base of the stock, whose development would inhibit that of the scion, have to be removed, which is a tricky, lengthy and onerous task.
FR-A-86 01, 117 discloses a machine for grafting of green wood.